The disclosure relates generally to monitoring for indications of and/or fatigue failures, and more specifically, to detection of deviations from an expected operation that lead to fatigue failures of a rotary machine of an environmental control system.
In general, a system through overuse and untimely maintenance will have fatigue failures. Servicing methods addressing system fatigue failures include reactionary maintenance and maintenance checks. Reactionary maintenance is an action that is in direct response to clear signs of a pending fatigue failure or an actual fatigue failure. A clear fatigue failure sign is any recognizable event, such as noise or smoke, from a system. A fatigue failure is a system breakdown, which may result from neglecting clear fatigue failure signs or from unavailability of such signs prior to the fatigue failure. Maintenance checks are actions that search for clear fatigue failure signs before the resulting fatigue failure occurs. However, reactionary maintenance and maintenance checks put the system out-of-commission until the servicing method is complete, thereby negatively affecting an operation time of the system.
For example, in an aircraft environment, an air cycle machine connected to an environmental control system utilizes an air cycle cooling process to output cool air directly into an aircraft cabin or onto electronic equipment for ventilation/cooling. If the air cycle machine exhibits a clear fatigue failure sign (e.g., smoke generation, unexpected operation noise, etc.) or has a fatigue failure (e.g., fatigue failure of fan blades, blade loss, blade/housing contact, etc.), the air cycle machine must receive reactionary maintenance. Yet, reactionary maintenance is costly, as a usual result is to entirely replace the fatigued air cycle machine, which puts the aircraft unexpectedly out-of-commission until the reactionary maintenance is complete. Further, rather than wait for an air cycle machine to exhibit a clear fatigue failure sign or have a fatigue failure, the air cycle machine may go through scheduled maintenance checks. Yet, like reactionary maintenance, scheduled maintenance checks are also costly because these checks guarantee that the aircraft will be regularly out-of-commission, while providing no guarantee that the scheduled maintenance checks will discover a fatigue failure.